A horrific attack on a paramilitary force practicing for a parade in the Yemeni capital has left more than 90 dead and hundreds injured. A man dressed as a soldier apparently detonated a belt packed with explosives, setting off a blast that littered the square near the presidential palace with limbs and heads and blood. The BBC reported an al-Qaeda source saying the organization claimed responsibility for the suicide bombing. The carnage in Sana'a takes place as the government is in the middle of a major campaign against al-Qaeda, as TIME's Tom Finn originally filed last week in the story below:

A chorus of wailing muezzins and rattling windowpanes awoke residents of Yemen's capital Sana'a on Friday as a sortie of government fighter jets dipped over mountains to the north and screamed across the city. The country is now seeing the largest military offensive in its history  the battle to uproot al-Qaeda in the Arabian Peninsula (AQAP). And America is intimately involved in this war, providing arms, training and intelligence to Yemen's armed forces as it pursues this fierce new war in the Middle East. The Pentagon believes AQAP may have established the most dangerous base of operations in the Arab world.

A plot last month by the group to blow up a U.S.-bound airliner  the third attempt in as many years  was scotched by a CIA undercover agent masquerading as a suicide bomber. The incident proved incentive enough for Yemen to ratchet up its 10-year fight against jihadism supported by the United States.

Yemen had slipped off the radar since last year when mass protests, mutinying generals and looming international sanctions helped unseat the country's strongman, Ali Abdullah Saleh, after 33-years in power. Though a political transition is underway, the country remains on a knife-edge. Shi'a rebels, southern separatists, and a famine brought on by a crippled economy are all sapping Yemen's efforts to build a new political order. But it is a group of al-Qaeda fighters in the south, who have driven out government forces and set up "Jihadi emirates"  mini Islamic fiefdoms  who now pose the gravest threat to the country.

Sweeping east from the southern port city of Aden and backed by heavy artillery and warplanes, thousands of Yemeni soldiers using tanks and Katusha rockets are trying to dislodge al-Qaeda from their lairs and strongholds in the mountains of Abyan province. Hunkered down amongst residents of local towns and villages the militants are using Duskas (Soviet-era heavy machine guns) and artillery they seized in forays on army outposts to stave off the army's advance. "They [al-Qaeda] are fighting a guerrilla war. Hiding amongst civilians... fighting us tooth and nail with our own weapons," says Brigadier General Mohammed al-Sawmli, whose Brigade 25 was pinned down for months by the Islamic militants last year after Yemeni security forces abandoned Abyan. "Every time we seize new ground they try to take it back. They prefer dawn raids so our men are getting little sleep, but God willing we will prevail."

With Sana'a busy trumpeting the military's advances on the evening news it is ordinary Yemeni citizens, not soldiers, who appear to be turning the tide against the jihadists. Residents of Lawder, a strategic town nestled among Abyan's rugged mountains and a scene of much of last week's fighting, have organized themselves into civilian groups known as "popular committees." Using arms left behind by deserting army brigades, the committees have held off daily assaults on the city by al-Qaeda for months.

Ali Eidha, spokesman for a committee called 'the sons of Lawder,' said his tribesmen, fighting alongside the army, were pushing al-Qaeda back. "Yesterday we took back Jabal Yasouf," he says over the phone, referring to a strategic mountain above Lawder that controls access to other al-Qaeda held towns in Abyan. "After the dawn prayer warplanes began bombing their positions from the sky, then we ascended up the mountain, arresting and driving al-Qaeda off the hillside. Afterwards we lit fires on the hilltops in celebration." Eidha said his men had found the corpses of 12 Yemeni soldiers in a ditch on the mountaintop; their heads and hands missing. "They call themselves Muslims but they are barbarians," says Eidha. "They do not understand mercy."

Since assuming the presidency in February, Abd Rabu Monsur Hadi, Saleh's former deputy, a renowned political lightweight, has bucked expectations  shaking up the military and purging Saleh's loyalists from key posts in an effort to break up webs of patronage and cronyism still controlled by his predecessor. Whereas Saleh's relationship with Washington blew hot and cold  strained by suspicions that he was encouraging al-Qaeda to extract more funds from Washington, Hadi  who has bullish pledges of support for the U.S. and has made belligerent threats against the terror group  has taken on the image of an incensed warlord. "The pursuit of terrorists is irreversible," Hadi told Washington's chief counter-terrorism czar, John Brennan, in a meeting in Sana'a this week. Brennan, a military strategist who is America's chief liaison with Yemen, responded with a verbal pat on the back: "You are making historical decisions during these critical times in modern day Yemen."

Nevertheless, while Hadi may wish to ensure the continued flow of billions of U.S. dollars to his near-empty government coffers, his rapport with the Americans is making him vulnerable to domestic political sniping. On Thursday al-Qaeda released a video portraying Hadi as a stooge of Saleh and an "agent" of the United States. "The corrupt [Yemeni] forces have agreed to fight the Mujahideen under the American flag and with Saudi funding," said al-Qaeda's leader Ayman al-Zawahri in the video. "The country should be cleansed from corrupt politicians who suck the people's blood like vampires ... and move towards building a Muslim Yemen governed by God's law." A web banner linking to the video uses graphics to dress up Yemen's new president in an Uncle Sam suit.

Zawahiri's rhetoric can usually be dismissed as extremist ramblings. However, U.S. policy in Yemen is indeed breeding widespread anti-American sentiment. An expansion of U.S. drone attacks in Yemen, endorsed by the Obama administration last month, has whipped up discontent among a population that views American influence as an encroachment on sovereignty. Many Yemenis see Gerald Feierstein, the U.S. ambassador, as the public face of a cruel military campaign that all too often misses its targets. In December 2009, a U.S. cruise missile crashed into a caravan of tents in the rural south, killing dozens, among them 14 women and 21 children.

"Further civilian casualties from airstrikes, whether inflicted by the U.S. or not strengthen the logic and appeal of al-Qaeda," says Farid Al- Zahar, a politics professor from Aden University. "Every time an airstrike kills a civilian al-Qaeda can point and say, 'look, your government not only neglects you, it allows Americans to kill your people. What kind of government is that? Is it a government you want to work with or a government you want to fight and destroy?"